Preheat your oven to 400°F and line a large rimmed baking sheet with unbleached parchment paper for easy cleanup.
Scrub the sweet potato and dice into 1/2-inch cubes; chop the broccoli into small florets and slice the bell pepper into bite-sized pieces.
Slice the chicken breast into 1-inch pieces, ensuring they are uniform in size to cook evenly alongside the vegetables.
In a large mixing bowl, whisk together the extra virgin olive oil, fresh lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Add the chicken and all the chopped vegetables to the bowl, using your hands or a spatula to coat every piece thoroughly in the marinade.
Spread the mixture onto the prepared baking sheet in a single layer, making sure not to overcrowd the pan so the edges get nicely caramelized.
Roast for 20 to 22 minutes, tossing halfway through, until the chicken is golden and the sweet potatoes are tender when pierced with a fork.
Remove from the oven and garnish with fresh parsley if desired, serving immediately while the flavors are vibrant and the chicken is juicy.